Reagan would never consent to being VP, especially back then when the VP was weaker.I would have picked Reagan early on, so no primary fight from here. So I could focused on Carter.
Ford later said that letting Rockefeller go was a big mistake, maybe he is convinced to stay on?
John Connally maybe?
Howard Baker, definitely.
With Baker, Ford could win Tennesee and Ohio and the election. fFord 275 Carter 262 rReagan 1
His most obvious alternative choice would be his main opponent in the primaries, Ronald W. Reagan. This would hopefully serve to unite the moderate and conservative wings of the GOP together early on, allowing Ford to get his resources focused on winning the election.
I think Reagan knew that Ford was not going to win re-election when he lost the nomination - a lot of accounts of the period (you can read more in Donald Regan's memoirs) hint as much.